The CacheRoot directive defines the name of
the directory on the disk to contain cache files. If the mod_disk_cache module has been loaded or compiled in to the
Apache server, this directive must be defined. Failing to
provide a value for CacheRoot will result in
a configuration file processing error. The CacheDirLevels and CacheDirLength directives define
the structure of the directories under the specified root directory.

The CacheSize directive sets the desired
disk space usage of the cache, in KBytes (1024-byte units). This
directive does not put a hard limit on the size of the cache. The
garbage collector will delete files until the usage is at or below the
settings. Always use a value that is lower than the available disk
space.